| **Welcome to the Flutter API reference documentation!** | |
| Flutter is Google's SDK for crafting beautiful, fast user experiences for | |
| mobile, web, and desktop from a single codebase. Flutter works with existing | |
| code, is used by developers and organizations around the world, and is free | |
| and open source. | |
| This API reference covers all libraries that are exported by the Flutter | |
| SDK. | |
| ### More Documentation | |
| This site hosts Flutter's API documentation. Other documentation can be found at | |
| the following locations: | |
| * [flutter.dev](https://flutter.dev) (main site) | |
| * [Installation](https://flutter.dev/docs/get-started/install) | |
| * [Codelabs](https://flutter.dev/docs/codelabs) | |
| * [Contributing to Flutter](https://github.com/flutter/flutter/blob/master/CONTRIBUTING.md) | |
| ### Importing a Library | |
| #### Framework Libraries | |
| Libraries in the "Libraries" section below (or in the left navigation) are part | |
| of the core Flutter framework and are imported using | |
| `'package:flutter/<library>.dart'`, like so: | |
| ```dart | |
| import 'package:flutter/material.dart'; | |
| import 'package:flutter/services.dart'; | |
| ``` | |
| #### Dart Libraries | |
| Libraries in the "Dart" section exist in the `dart:` namespace and are imported | |
| using `'dart:<library>'`, like so: | |
| ```dart | |
| import 'dart:async'; | |
| import 'dart:ui'; | |
| ``` | |
| Except for `'dart:core'`, you must import a Dart library before you can use it. | |
| #### Supporting Libraries | |
| Libraries in other sections are supporting libraries that ship with Flutter. | |
| They are organized by package and are imported using | |
| `'package:<package>/<library>.dart'`, like so: | |
| ```dart | |
| import 'package:flutter_test/flutter_test.dart'; | |
| import 'package:file/local.dart'; | |
| ``` | |
| ### Packages on pub.dev | |
| Flutter has a rich ecosystem of packages that have been contributed by the | |
| Flutter team and the broader open source community to a central repository. | |
| Among the thousands of packages, you'll find support for Firebase, Google | |
| Fonts, hardware services like Bluetooth and camera, new widgets and | |
| animations, and integration with other popular web services. You can browse | |
| those packages at [pub.dev](https://pub.dev). |